TOKYO -- Prime Minister Yoshihiko Noda dissolved the lower house of parliament Friday, paving the way for elections in which his ruling party will likely give way to a weak coalition government divided over how to solve Japan's myriad problems.

Elections were set for Dec. 16. If Noda's center-left party loses, the economically sputtering country will get its seventh prime minister in seven years.

"Banzai! Banzai! Banzai!" shouted the 480-some lawmakers in the lower house, raising their arms each time in celebration, after the house speaker read a proclamation approved by Emperor Akihito, delivered wrapped in a cloth of imperial violet.

The opposition Liberal Democratic Party, which led Japan for most of the post-World War II era, is in the best position to take over. The timing of the election likely pre-empts moves by more conservative challengers, including former Tokyo Mayor Shintaro Ishihara, to build up electoral support.

Campaigning is set to begin Dec. 4, but leaders were already switching into campaign mode.

"What's at stake in the upcoming elections is whether Japan's future is going to move forward or backward," Noda declared to fellow leaders of the Democratic Party of Japan. "It is going to be a crucial election to determine the fate of Japan."

The DPJ, in power for three years, has grown unpopular thanks largely to its handling of the Fukushima nuclear crisis and especially its recent doubling of the sales tax.

Noda's most likely successor is LDP head and former Prime Minister Shinzo Abe. He resigned as Japan's leader in 2007 after a year in office, citing health problems he says are no longer an issue.

"I will do my utmost to end the political chaos and stalled economy," Abe told reporters Friday. "I will take the lead to make that happen."

The path to elections was laid suddenly Wednesday during a debate between Abe and Noda. Noda abruptly said he would dissolve parliament if the opposition would agree to key reforms, including a deficit financing bill and electoral reforms, and Abe jumped at the chance.

Polls indicate that the conservative, business-friendly LDP will win the most seats in the 480-seat lower house but will fall far short of a majority. That would force it to cobble together a coalition of parties with differing policies and priorities.

"It's unlikely that the election will result in a clear mandate for anybody," said Koichi Nakano, a political science professor at Sophia University. "So in that sense, there's still going to be a lot of muddling through."

The election, and the divided government that will follow, complicate efforts to extricate Japan from its two-decade economic slump and effectively handle the cleanup from its 2011 nuclear disaster.

Still, many saw the prospect of change as positive: Japan's Nikkei 225 stock index jumped 2.2 percent Friday to close at 9,024.16.

Japan's leaders urgently need to devise strategies for coping with a soaring national debt, now more than double the national GDP, and a rapidly aging population. Japan must also decide whether it will follow through with plans to phase out nuclear power by 2040 - a move that many in the LDP oppose.

Perhaps most pressing is Japan's festering territorial dispute with China, which has hammered exports to its biggest trading partner.

A staunch nationalist, Abe has railed against China in the dispute over a cluster of uninhabited islands in the East China Sea controlled by Japan but also claimed by China and Taiwan.

Japan is going through a messy political transition, with a merry-go-round of prime ministers and the emergence of various parties to challenge the long-dominant LDP.

The Democratic Party of Japan's ousted the LDP in a 2009 landslide, raising hopes for change. But the DPJ's failure to keep campaign promises and the government's handling of the Fukushima nuclear crisis triggered by the March 11, 2011, earthquake and tsunami have left many disillusioned. Noda's centerpiece achievement during nearly 15 months in office was a highly unpopular bill doubling the 5 percent national sales tax by 2015.

Polls show support for the DPJ in the low teens, while 25 to 30 percent of voters back the LDP. Several other parties have lower levels of support, and nearly half the electorate is undecided.

"There are so many lying politicians," said Tokyo resident Michiyo Komaki. "I just wish for a leader who would do his job properly."

Ishihara recently resigned as Tokyo mayor to create the Sunrise Party. As mayor, he helped instigate the territorial crisis with China by declaring that Tokyo would buy and develop the disputed islands controlled by Japan but long claimed by Beijing. The central government bought the islands itself, intending to thwart Ishihara's more extreme plans, but China was still enraged.

Ishihara has been courting Toru Hashimoto, the young, outspoken mayor of Osaka, Japan's second biggest-city, in hopes of tapping voter dismay. Both have formed their own national political parties, but they may not have enough time to get organized for the election.

The two men are reportedly in discussions to merge their parties and form a so-called "third force" to counter the LDP and DPJ, but apparently are struggling to reconcile conflicting policy views, including on nuclear power.

"The era of one-party dominance is clearly over and behind us," said Nakano, the professor. "We know what we are transiting from, but we don't know where we are going."